John Prescott has backed Tony Blair's controversial school reform plans for England, saying they modernise the principles of comprehensive education.
The deputy prime minister has been the most senior critic of the proposals to date, fearing "trust" schools could lead to a two-tier education system.
But in a speech in Hull he said the reforms could produce a "step change" in standards and harness parent power.
His support comes as ministers finalise a series of compromises on the reforms.
Local authorities are set to be given a stronger role and the schools admissions code would be given more legal teeth.
Mr Blair is also thought to be considering banning schools from interviewing parents as part of the admissions process.
Many Labour MPs believe such interviews will mean a return, by the "back door", to selecting pupils by academic ability, outlawed when the 11-plus was scrapped.
Mr Blair is understood to be thinking through all the options this weekend.
Another possible concession is allowing local councils, not just businesses, charities or voluntary groups, to build new schools.
The government's Education White Paper, published last year, proposed setting up schools independent of local authority control, allowing them more say over admissions and budgets.
But more than 90 Labour MPs have criticised the plans.
Mr Prescott went public with his reservations about the education plans last year and on Friday admitted he, like many people, had been concerned.
But he said the proposed changes were in line with Labour's drive to improve education for people from all backgrounds.
"I believe that the Education White Paper, followed by the Education Bill, will provide a proper balance of flexibility, of power, or responsibilities and yes of greater accountability," he said.
"It will strengthen and modernise the comprehensive education system. It will continue the great education achievements under the Labour government since 1997."
Mr Prescott said he wanted to keep the comprehensive principles of avoiding academic selection.
And he rubbished suggestions he did not want good schools, saying he wanted to ensure quality education for everybody, not just the privileged few.
"I make no apology that my politics is informed by who I am and where I came from: I was an 11-plus failure who was luck to get a second chance," he said.
The outline of the government's possible compromise emerged on Thursday.
Local authorities are to be offered "strategic oversight" of all state schools and schools would have to act in accordance with the admissions code, not just "have regard" to it.
The revised plans appear to reinforce the role of existing admissions forums, which seek to co-ordinate admissions in an area.
It is thought the government might change the plans so schools have to abide by what forums agree.
Work on the final details of the compromise package, expected to be completed by the end of next week, is continuing.
Last month, the Commons education select committee called for more safeguards, such as schools having "benchmarks" for taking pupils from poorer backgrounds.
Conservative members of the committee published their own report demanding that the government presses ahead with the full reforms.
Tony Blair is thought to want to avoid relying on Conservative support for the measures to get through Parliament.
Tory shadow education secretary David Willetts said he feared the compromise plans showed Mr Blair was seriously worried about Labour backbenchers.
"Instead of negotiating with Labour backbenchers, I hope what he would think about above all is the interests of pupils and their parents," he said.
Labour MP Martin Salter, who resigned as a ministerial aide over the school reforms, welcomed the new "mood music" from the government.
"I am delighted that small steps are being taken in the right direction but there is a long way to go yet," he told BBC News.